At present, a computer case is generally provided therein with an expansion slot, via which a graphics card, a network card, and the like are installed in the computer case. These peripherals such as a graphics card and a network card that are installed in the computer case via an expansion slot are usually referred to as expansion cards. The prior expansion cards mostly contain a USB port, an audio port, etc., and are mostly used for data transmission, and cannot be used as a power supply device to supply power to peripherals plugged into the expansion cards, and thus have a limited range of application.